1. Field of the Invention
The present invention relates to a flexible container having a specific structure consisting of a rubber coated fabric or the like and adopted to contain and transport liquid; a liquid transport method and apparatus using the container, and a method and facility for washing the container.
2. Description of the Related Art
Conventionally, in a case where specific liquid is transported by means of a vehicle exclusive for liquid transport, equipped with a tank, there is no inconvenience if such specific liquid is housed and transported on a way to go and another liquid is housed and transported on a way to return. However, in a case where no liquid is transported on a way to return, the vehicle has to return with only empty containers, which is extremely inefficient from an economical aspect.
In order to solve such problem, Japanese Patent Laid-open Publication No. 3-275485 and Japanese Utility Model Laid-open Publication No. 5-13993, for example, disclose flexible containers for liquid transport, in which the liquid is contained in a foldable flexible container, transported to a destination, and replaced into another container at the destination. Thereafter, the flexible container is folded, which has made it possible to load another ordinary carriage on a returning vehicle and transport it on a way to return. All of these containers are provided with liquid injecting and ejecting ports.
In the meantime, in a case where the flexible container is loaded in a freight container and transported while liquid is contained therein, the liquid is less moved, and the flexible container is less deformed during constant-speed running when a vehicle runs at a constant speed without any acceleration or deceleration. However, at the braking, startup, or acceleration of the vehicle, the liquid moved in the forward and backward direction due to inertia, so that the flexible container for liquid transport is locally swelled at its upper portion. As a result, local distortion is repeatedly generated at the flexible container for liquid transport, whereby its durability is lowered. In particular, the liquid is significantly moved due to inertia caused by braking. When the vehicle brakes, particularly in sudden stoppage, the rate of swelling of the flexible container becomes greater than that made in the other acceleration or deceleration. Thus, a shocking load acts to an driver at every braking, so that the subsequent driving is impaired.
According to suggestions of the above publications, there is adopted a structure in which deformation due to the liquid movement of the container is reduced to the minimum in order to eliminate the lowered durability of the flexible container or discomfort of the driver as described above. in Japanese Patent Laid-open Publication No. 3-275485 for example, the Young's module of a material for a ¼ portion at the forward side of the container, especially the upper part of it, which is the most deformable during braking, is set to be greater than that of the other portion so as to reinforce the material. Alternatively, in the aforementioned Japanese Utility Model Laid-open Publication No. 5-13993, a band is secured to a peripheral face of a cylindrical flexible container at a height which is ½ or less from a bottom face thereof, or a core material reinforcing layer and a highly elastic element are laminated integrally with each other in order to enhance rigidity.
In this manner, because the lowered durability of the flexible container or discomfort of the driver can be eliminated, advantageous effect of transport using a flexible container of such type as described above has been increased. In the recent years, in food industries such as drinks or food oil, attention is focused on transport using these flexible containers. In particular, if it becomes possible to transport fresh milk or various juices or the like contained in the containers from a source to a consuming area, the transport efficiency is improved as described above, which is economically profitable considering the price of the container. Hence, in edible liquid of such type, the freshness is most essential. Moreover, it is greatly restricted from the viewpoint of food sanitation.
Specifically, if liquid to be transported by a flexible container of such type is edible liquid , drinks or the like, the inside of the container must always be cleaned and sanitarily controlled. After having been transported, therefore, the aforementioned flexible container is subject to liquid treatments such as washing, sterilization, and disinfecting treatments. In order to facilitate these treatments, according to the specification of U.S. Pat. No. 3,965,953 for example, an air tight and water resistant slide fastener of 5 cm in length is mounted to a center of an upper surface in a longitudinal direction of an elongated flexible container having its liquid capacity of 1 m3, so that the fastener mounted portion can be opened and closed.
In the flexible container disclosed in the U.S. Pat. No. 3,965,953 specification, a slit-shaped opening is formed openably on the center of the upper surface of the container by means of an air tight water resistant slide fastener. With only such a small slit shaped opening, however, there has been a problem that an attempt to surely wash, sterilize, or disinfect the inside of the container has been extremely cumbersome. In particular, the subsequent drying treatment requires long time.
On the other hand, in a case where a flexible container containing a liquid is loaded and transported on the exclusive, the liquid is less moved in the flexible container and the container is less deformed during constant-speed running when the vehicle runs at a constant speed without acceleration or deceleration as indicated by solid line in FIG. 35. However, during braking, startup, or acceleration of the vehicle, the liquid is moved in the forward and backward direction of the vehicle due to inertia, and there occurs a phenomenon that the flexible container is locally swelled as indicated by two short dotted lines in the figure. In particular, such swelling occurs in a wave-shape at the upper portion of the flexible container.
As in the flexible container disclosed in the U.S. Pat. No. 3,965,963 specification, in the case where an airtight water resistant slide fastener is mounted to the upper surface portion of the flexible container, a large stress is repeatedly applied to the air tight water resistant slide fastener due to the repeated swelling of the flexible container. As a result, the air tightness and water resistance of the slide fastener are lowered, and liquid leakage occurs.
Further, in the flexible container disclosed in the USP specification as well as the flexible container disclosed in the above publication, it is impossible to spread the container itself. Even if washing is performed for every transport, visual check cannot be performed, which makes it impossible to ensure that the inside of the container is surely cleaned.